HYDROLOGICAL INSTRUMENTS 



and this, when the shaft is at its lowest, is housed within the 

 conical upper part of the instrument. The cast-iron sinkers g each 

 have a hole in the middle through which the rod passes and they 

 are suspended by a bight of wire to the projection /. When the 

 instrument strikes the bottom the rod is driven backwards, the 

 wire is disengaged from /by the conical head-piece, and the sinkers 

 are detached. As will be seen from the figure the sinkers are of 

 two shapes, conical and flat, the former being 23 lb. and the latter 

 20 lb. in weight. For most deep-water soundings it was customary 

 to use four sinkers — two cones with two flats between. 



These two pieces of apparatus proved very reliable : except on 

 rocky ground they rarely failed to provide a sample of the bottom. 



Snapper leads, with both fixed and detachable weights, were 

 also used on a few occasions, but appeared to be less certain in 

 their action. The " Sondeur Leger ' V a light form of grab originally 

 constructed for the Prince of Monaco, was sometimes employed 

 for obtaining larger samples of the bottom in shallow water, but 

 as already stated the conical dredge was used for this purpose 

 during the trawling operations of the 'William Scoresby'. 



For obtaining cores of ooze in deep water an instrument similar 

 to that described by Ekman- in 1905 was constructed. It is similar 

 in principle to the Baillie rod, but is much longer and carries 

 glass tubes inside which can be withdrawn without disturbing the 

 enclosed bottom sample. This instrument, which is illustrated in 

 Fig. 32, differs from the Ekman-Nansen pattern in that the weight 

 is detachable — a necessity for deep-water work. As in the Baillie 

 rod there is a mushroom valve at the top of the tube ; closure at the 

 bottom end is effected by two cup-shaped valves, actuated by a 

 spring and similar to those used in snapper leads, which slide down 

 the outside of the tube when the sinker is released. The rod is 

 5 ft. 2 in. in length and contains three 15 in. glass tubes separated 

 by thin leather washers. The internal diameter of the glass 

 tubes is about ij in., and the pear-shaped cast-iron sinkers are 

 53 lb. in weight. The instrument was made by the Telegraph 

 Construction and Maintenance Co. and with it cores up to 

 47 cm. in length have been obtained. Deeper penetration could 

 perhaps be eff'ected by using a heavier weight and a tube of smaller 

 diameter. 



ir.-ijr^ •■,- 1 r, , c 1 ^ ■ ,,^ F'K- 12. Modified form of 



Richard, Les Campagiies scientifiques de S.A.S. le Prince de Monaco, p. 17, |knian-Nansen sounding 



figs. 12-14, Monaco, 1910. 



^ Ekman, Pub. Circ, Cons. E.xplor. Mer, 27, pp. 1-6, 1905. 



rod, for obtaining cores 

 of ooze in deep water. 



